1. Field of the Technology
The present invention relates to network equipment location techniques and, more particularly, to a method of processing a periodic location request.
2. Background of the Invention
For Location Service (LCS) of mobile communication networks, location information of target User Equipment (UE) is obtained through positioning techniques, where UE denotes the UE terminal to be positioned in the mobile communication network, and location information may be either geographical latitude and longitude information or the location of local streets. Location information obtained by the mobile communication network may be provided to the target UE for self-positioning, or provided for the mobile network itself. Location information may alternatively be provided to other client application ends requesting the location of the target UE, such as organizations and individuals, for supplement service. Therefore, location service is of broad application in terms of emergency assistance, vehicle guidance, intelligence traffic system, work dispatching, team management, mobile yellow page inquiry and network performance enhancement, etc. LCS specifications as well as function mode, structure, state description and message flow of the whole LCS system are illustrated in The 3rd Generation Partnership Project (3GPP).
FIG. 1 is a schematic diagram illustrating logical structure of location service function. As shown in FIG. 1, as far as function logic is concerned, function logic entities for implementing location service include request end 101, LCS system 106 for implementing location service function entities and target UE 107. Function entities for implementing location service include Gateway Mobile Location Center (GMLC) 102, user data storage server 103, Central Network (CN) 104 and Radio Access Network (RAN) 105. Request end 101 may be composed of requester and LCS client end. LCS client end denotes a software or hardware entity, which is used for obtaining location information of one or more than one target UE 107 and accessed to GMLC 102; requester denotes an application client that requests for location information of target UE 107, such as an organization or individual, which initiates the location request, and LCS client end can also be a requester. GMLC 102 provides a standard LCS interface for information interaction between LCS client and function entities for implementing location service. In order to process location service messages, this process is as follows. Request end 101 is authenticated, and location request message sent by Request end 101 is authenticated. After the authentication, GMLC 102 sends the request for locating target UE 107 to CN 104, and lastly, GMLC 102 transmits the locating result of target UE 107 returned by CN 104 to Request end 101. User data storage server 103 is a Home Location Register (HLR) or Home Subscriber Server (HSS), used for storing user data and providing relevant information of target UE for other network logic entities, such as address information of the GMLC 102 to which target UE is affiliated, current GMLC 102 that target UE is located and address information of CN 104. CN 104 receives and processes the request for locating target UE 107 sent by GMLC 102, cooperates with RAN 105 to locate target UE 107, and returns the locating result of target UE 107 to GMLC 102.
GMLC may further include Requesting GMLC (R-GMLC), Home GMLC (H-GMLC) and Visited GMLC (V-GMLC). R-GMLC is a GMLC for receiving the location request initiated by LCS client to target UE, H-GMLC is a GMLC which the target UC belongs to, V-GMLC is the current GMLC that is working for target UE, and namely the GMLC that target UE is currently located. R-GMLC, H-GMLC and V-GMLC may be the same physical entity, or be different physical entities.
At present, in LCS 3GPP specification, location requests that LCS client sends to target UE are divided into two categories, namely immediate location request and deferred location request. As to immediate location requests, after LCS system receives the location request that LCS client sends to target UE, target UE is immediately located, and then location result of target UE is returned to LCS client. LCS system immediately returns location result of target UE to LCS client immediately upon receiving the location request sent by LCS client. As to deferred location request, LCS client demands LCS system to provide location information of target UE at a future time or when a certain event is detected. After receiving the location request that LCS client sends to target UE, LCS system needs to wait for a period, and returns the location result of target UE to LCS client after the deferred event is detected.
In addition, 3GPP allows LCS client to demand LCS to periodically provide location information of target UE. LCS client defines starting time and ending time as well as certain periodic logic, and demands LCS system to provide location information of target UE in this period of time according to the periodic logic. Besides, periodic location request and deferred location request may be combined. LCS client can send periodic deferred location request to LCS system.
FIG. 2 is a processing flowchart of periodic deferred location request in LCS specification of 3GPP. As shown in FIG. 2, the process of periodic deferred location request defined in LCS specification of 3GPP, which is associated by UE available deferred location request and periodic location request, includes the following steps.
Step 201: LCS client sends periodic deferred LCS Service Request to R-GMLC, and requests LCS system to provide location information of target UE, where the LCS Service Request carries target UE identifier and triggering events for locating target UE. For instance, as soon as being attached to mobile network, target UE will immediately be located. This LCS Service Request also carries certain periodic logic, namely start periodic timer, periodic ending time and time interval for locating target UE.
Step 202: after receiving the location information that LCS client sends to target UE, R-GMLC starts periodic timer at start periodic time according to periodic logic, and sends common deferred LCS Service Request to H-GMLC/V-GMLC, where the LCS Service Request carries the triggering event for locating target UE, as well as Reference Number allocated for common deferred LCS Service Request by R-GMLC, like 1234.
Steps 203-205: after receiving LCS Service Request, H-GMLC/V-GMLC sends Provide Subscriber Location request to CN, where the Provide Subscriber Location carries triggering event for locating target UE, as well as Reference Number allocated for common deferred LCS Service Request by R-GMLC, requesting CN to locate target UE when triggering event is detected. After receiving Provide Subscriber Location, CN judges whether triggering event condition is satisfied, target UE will be directly located if the condition is satisfied, otherwise, CN stores triggering event and Reference Number of target UE which is to be located, and then sends Provide Subscriber Location Acknowledgment (ACK) to H-GMLC/V-GMLC, notifying H-GMLC/V-GMLC that CN has accepted the common deferred location request sent by target UE. After receiving Provide Subscriber Location ACK, H-GMLC/V-GMLC sends LCS Service Response to R-GMLC, notifying R-GMLC that CN has accepted the common deferred location request sent by target UE; after receiving LCS Service Response, R-GMLC sends LCS Service Response to LCS client, where the LCS Service Response carries the Reference Number allocated for the current common deferred LCS Service Request by R-GMLC, notifying LCS client that LCS system has accepted the deferred location request sent to target UE by LCS client.
Step 206: when periodic timer of R-GMLC is timeout, and then R-GMLC judges whether it is in a state waiting for CN to return location result of target UE, and if yes, step 207a is executed. Otherwise, step 207b is executed.
The specific process of R-GMLC in state of waiting for CN to return location result is as follows.
Step 207a: R-GMLC sends LCS Service Response to LCS client, where the LCS Service Response carries the Reference Number allocated in step 202 by R-GMLC, so as to notify LCS client that location information of target UE is not to be provided.
Steps 208a and 209a: CN judges whether current occurrence condition of the stored triggering event is satisfied, and if yes, directly locating target UE, otherwise, continuing to wait for triggering event occurrence. When CN detects that triggering event has been detected, for instance, as for UE available deferred location request, LCS client requests to locate target UE as soon as target UE is accessed to mobile network. Here, when target UE requests access to mobile network, CN assumes that triggering event for locating this target UE has been detected, and CN cooperates with RAN to perform Location Procedure to target UE.
Steps 210a-212a: after finishing cooperating with RAN to locate target UE, CN sends Subscriber Location Report to H-GMLC/V-GMLC, where the Subscriber Location Report carries location result of target UE, as well as Reference Number stored by CN, like 1234. After receiving Subscriber Location Report, H-GMLC/V-GMLC sends Subscriber Location Report ACK to CN, notifying CN that location result of target UE has been received. Meanwhile, H-GMLC/V-GMLC sends LCS Service Response to R-GMLC, where the LCS Service Response carries the location result of target UE returned by CN, as well as Reference Number. After receiving LCS Service Response, R-GMLC may perform transform process to the received location result of target UE on need, say transforming latitude and longitude information into local physical information. R-GMLC sends LCS Service Response to LCS client, and provides the transformed final location information of target UE for LCS client, where the LCS Service Response carries the Reference Number. Then, R-GMLC turns to the state of not waiting for CN to return location result.
The specific process of R-GMLC not in state of waiting for CN to return location result is as follows.
Steps 207b-209b: R-GMLC resends common deferred LCS Service Request to H-GMLC/V-GMLC, where this LCS Service Request carries the triggering event for locating target UE, as well as the Reference Number of current common deferred LCS Service Request reallocated by R-GMLC, like 5678. Here, because this Reference Number is reallocated for current common deferred LCS Service Request by R-GMLC, this Reference Number is different from that allocated by R-GMLC in step 202. Subsequent steps are basically the same as steps 203-205, the difference being that Reference Number concerned in subsequent steps is different from that in steps 203-205.
Steps 210b-214b and steps 208a-212a are basically the same, the difference being that Reference Number concerned in steps 210b-214b is different from that in steps 208a-212a. 
Procedure in each subsequent period is basically the same as that in the above-mentioned process.
The above-mentioned Reference Number is allocated and maintained by R-GMLC. In the procedure of processing periodic deferred location request, R-GMLC allocates a Reference Number for each to-be-processed single deferred location request respectively, and provides this Reference Number for CN through H-GMLC/V-GMLC. CN then stores this Reference Number. After finishing locating target UE, CN returns the location result of target UE to R-GMLC through H-GMLC/V-GMLC, carries the stored Reference Number, so that R-GMLC can associate this location result with the location request starting this locating procedure. In addition, when R-GMLC notifies LCS client that LCS system has accepted the location request that LCS client started, the Reference Number previously allocated for current under-process single deferred location request is provided for LCS client. Moreover, when returning location result of target UE to LCS client, R-GMLC carries the same Reference Number, so that LCS client can associate the received location information of target UE with the location request starting this locating procedure.
When LCS client cancels the previously started active location request, Reference Number is carried in cancellation request, so as to notify R-GMLC to cancel the location request corresponding to this Reference Number.
From the above description it can be seen that, according to the periodic logic provided by LCS client, LCS system divides the periodic deferred location request into several common deferred location requests. In the processing procedure, each divided location request is processed as a deferred location request, where Reference Number is allocated for the current under-process deferred location request, in order to identify this location request. In this way, LCS system will randomly allocate multiple Reference Numbers for those common deferred location requests, which are included in periodic deferred location request started by LCS client, such that Reference Numbers of the common deferred location request are different. Therefore, as to the same periodic deferred location request, LCS client will receive multiple responses with different Reference Numbers. Accordingly, LCS client cannot associate the self-starting periodic deferred location request with the response which is subsequently allocated Reference Number by LCS system, nor with location result of target UE. For instance, in the processing flowchart of FIG. 2, R-GMLC allocates a Reference Number 1234 for the first common deferred location request, and notifies LCS client in step 205 that Reference Number of periodic deferred location request previously started is 1234. Therefore, LCS client holds that only the location information response with Reference Number 1234 returned by LCS system is response of this periodic deferred location request. However, R-GMLC allocates a Reference Number 5678 for the second common deferred location request, and in step 209b, R-GMLC sends LCS Service Response with Reference Number 5678 to LCS client, in order to notify LCS client that the periodic location request has been accepted. Consequently, LCS client is unable to determine which previous location request this response is associated with, leading to uncertainty of the received location result of target UE. Moreover, in the above situation, when LCS client sends cancel message with Reference Number 1234 to LCS system, wishing to cancel the previously sent periodic deferred location request, as Reference Number of this request is 5678 in LCS system hereby, LCS system cannot find out the current active location request with Reference Number 1234, and is consequently unable to cancel this deferred location request correctly.